The theory that depression is caused by a chemical imbalance is often presented in the media as fact even though there is no scientific evidence to support it.

A review of a full set of trial data published in the journal PLoS (Public Library of Science) Medicine in 2008, and conducted by Kirsch et al., concluded that much of the perceived efficacy of several of the most common SSRIs (anti-depressants) was due to the placebo effect.

The fact is that many people do gain benefits by taking anti-depressants, but they also get well by taking sugar pills. This is the placebo effect, where what a person tells themselves when taking medicine or what they think it will do may happen, at least in the short term.

Jeffrey Lacasse, an FSU doctoral candidate and visiting lecturer in the College of Social Work, and Jonathan Leo, a neuroanatomy professor at Lincoln Memorial University in Tennessee, found that reporters who included statements in news articles about depression being caused by a chemical imbalance, or a lack of serotonin in the brain, were unable to provide scientific evidence to support those statements.

Lacasse and Leo spent about a year in late 2006 and 2007 monitoring the daily news for articles that included statements about chemical imbalances and contacting the authors to request evidence that supported their statements. Several reporters, psychiatrists and a drug company responded to the researchers’ requests, but Lacasse and Leo said they did not provide documentation that supported the chemical imbalance theory.

Their findings were published in the journal Society.

“The media’s presentation of the theory as fact is troublesome because it misrepresents the current status of the theory,” Lacasse said. “For instance, there are few scientists who will rise to its defense, and some prominent psychiatrists publicly acknowledge that the serotonin hypothesis is more metaphor than fact. As the current study documents, when asked for evidence, reporters were unable to cite peer-reviewed primary articles in support of the theory.”

“The chemical imbalance theory, which was formulated in the 1960s, was based on the observation that mood could be artificially altered with drugs, rather than direct observation of any chemical imbalances,” Leo said. “Since then there has been no direct evidence to confirm the theory and a significant number of findings cast doubt on the theory.”

The researchers said the popularity of the theory is in large part based on the presumed efficacy of the SSRIs, but they say that several large studies now cast doubt on this efficacy. Other studies indicate that for every 10 people who take an SSRI, only one to two people are truly receiving benefit from the medication, according to Lacasse and Leo.

According to the Australian Institute of Health and Welfare’s biennial report card, Australia’s Health 2010, there were still 12.3 million prescriptions written for antidepressants in 2008-2009. Further to this, an important study in 2008 conducted by Turner and colleagues, found that there has been a cover-up involved by not publishing research studies that showed that anti-depressants were ineffective.